What is the role of valve logic in a multi-actuator gear system?

• A. To ensure proper sequencing and prevent cross-actuation.
• B. To filter hydraulic fluid.
• C. To regulate cabin air flow.
• D. To provide lighting for the cockpit.

Answer: (A)

Valve logic coordinates how multiple gear actuators move together, making sure the right actuators get hydraulic pressure in the correct order and that they don’t fight each other. In a gear system with several actuators—for example, door actuators and main gear actuators—the logic acts as the control that sequences actions and locks out conflicting movements. This prevents cross-flow or simultaneous motions that could jam gears, crash doors into gear, or cause an unsafe configuration.

Think of it as the sequence manager: it ensures the doors open before the gears extend, holds an actuator in position when needed, and only allows retraction after all parts are in a safe state. If a fault is detected, the logic can hold other movements to avoid damage or unsafe gear positions. In short, valve logic is about getting the gear and doors to move in the right order and preventing any accidental, contradictory actions.